Gamma Tucanae, Latinized from γ Tucanae, is a

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

Tucana, marking the toucan's beak. It is faintly visible to the naked eye with an apparent visual magnitude of +3.99. Based upon an annual parallax shift of 43.37

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as seen from Earth, this star is located about 75

light year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s from the Sun. It is moving away from the Sun with a

radial velocity The radial velocity or line-of-sight velocity, also known as radial speed or range rate, of a target with respect to an observer is the temporal rate of change, rate of change of the distance or Slant range, range between the two points. It is e ...

of +18 km/s. There is disagreement in the literature as to the

stellar classification In astronomy, stellar classification is the classification of stars based on their stellar spectrum, spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a Prism (optics), prism or diffraction grati ...

of this star. Malaroda (1975) has it catalogued as F1 III, which would suggest it is an

evolved Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation t ...

F-type giant star. Houk (1979) listed it as F3 IV/V, which appears to indicate a less evolved F-type star transitioning between the

main sequence In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Her ...

and subgiant star. Gray et al. (2006) has it classed as F4 V, which would match an ordinary F-type main-sequence star. This star is a suspected

astrometric binary A binary star is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in wh ...

. The visible component has 1.55 times the

mass of the Sun The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass ...

and 2.2 times the Sun's radius. At the age of around 1.4 billion years, it retains a relatively high rate of spin with a

projected rotational velocity Stellar rotation is the angular motion of a star about its axis. The rate of rotation can be measured from the spectrum of the star, or by timing the movements of active features on the surface. The rotation of a star produces an equatorial bulge ...

of 94 km/s. It is radiating 11 times the Sun's luminosity from its

photosphere The photosphere is a star's outer shell from which light is radiated. The term itself is derived from Ancient Greek roots, φῶς, φωτός/''phos, photos'' meaning "light" and σφαῖρα/''sphaira'' meaning "sphere", in reference to it ...

at an

effective temperature The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation. Effective temperature is often used as an estimate of a body's surface temperature ...

of 6,679 K. Gamma Tucanae may (95% chance) have a distant co-moving companion – a magnitude 6.64

G-type main-sequence star A G-type main-sequence star (Spectral type: G-V), also often, and imprecisely called a yellow dwarf, or G star, is a main-sequence star (luminosity class V) of spectral type G. Such a star has about 0.9 to 1.1 solar masses and an effective temp ...

of class G0 V designated HD 223913. This object has the same mass as the Sun and is separated from Gamma Tucanae by about .

References

{{DEFAULTSORT:Gamma Tucanae F-type giants Astrometric binaries Tucanae, Gamma Tucana (constellation) Durchmusterung objects

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